1. Field of the Invention
The present invention relates to an optical disc reproducing apparatus that can reproduce audio data recorded on an optical disc and can be operated at a variable reproducing speed.
2. Related Background Art
An optical disc reproducing apparatus for so-called DJ (disc jockey) is used in a dance hall, discotheque, or the like to edit and reproduce, while varying the reproducing speed, data (audio data) of a sound, music, voice, or the like within an audible frequency range digital-recorded on an optical disc.
Besides, there is a special reproducing operation called scratch reproduction in which a disc jockey, using an analog player for reproducing an analog-recorded disc, places the needle on the analog disc and turns the turntable back and forth quickly so as to generate scratch sounds.
In order to perform scratch reproduction on a conventional optical disc reproducing apparatus for a digital-recorded disc such as CD (compact disc), necessary audio data must be stored in a memory after a normal-speed reproduction operation is started. In doing this, however, already-reproduced audio data, that is, the data before the present reproducing position can be stored on the memory but not-yet-reproduced audio data, that is, the data after the present reproducing position cannot be stored on the memory and, therefore, is not available for the scratch reproduction.
For this reason, only possible way for performing scratch reproduction of any not-yet-reproduced audio data is to read the audio data actually from the optical disc and reproduce it at a varying speed operated in the scratch reproduction. However, if it is attempted to vary the reading speed of data from the optical disc quickly as above, the operation for detecting the audio data recorded on the optical disc becomes unstable and the operation for varying the reproducing speed is restricted. Thus, it is difficult to perform scratch reproduction during a normal-speed reproduction operation.
As a way for performing false scratch reproduction, there is available a method for processing audio data as if the reproducing speed is varied, in which the actual reproducing speed is not changed but some audio data is skipped or interpolated so that the apparent frequency of the audio data is varied. As compared to the scratch reproduction in which the reproducing speed of audio data is varied, however, this method involves a problem that the sound quality changes.
In performing scratch reproduction using audio data detected from an optical disc, it is a common practice that audio data necessary for the scratch reproduction is stored beforehand in a memory, separately from the audio data being reproduced from the optical disc at a normal speed, and the scratch reproduction is performed independently from the normal-speed reproduction. Because of this, it is impossible to combine the reproduction operation of an optical disc with the scratch reproduction operation so as to perform the scratch reproduction during the normal-speed reproduction and then return the operation to the normal-speed reproduction mode at the end position of the scratch reproduction as was done conventionally with an analog disc.
It is an objective of the present invention to provide an optical disc reproducing apparatus for reproducing a digital-recorded disc such as CD which can start scratch reproduction during normal-speed reproduction without terminating the reproduction of audio data from the optical disc and return to the normal-speed reproduction after the scratch reproduction is ended so as to perform similar scratch reproduction to that with an analog disc.
An optical disc reproducing apparatus in claim 1 of the invention comprises a pickup means for detecting digital audio data recorded on an optical disc, a storing means for storing the digital audio data detected by the pickup means, an input means for inputting the reproducing direction and reproducing speed of the digital audio data, a control means for controlling the reading and writing of the digital audio data from/into the storing means so as to control the reading direction and reading speed of the digital audio data stored on the storing means based on the reproducing direction and reproducing speed inputted from the input means, and a signal processing means for converting the digital audio data read from the storing means into an analog audio signal and outputting the analog signal, wherein the control means controls the reading and writing of the digital audio data from/into the storing means so that the volume of the digital audio data outputted from the signal processing means becomes equal to the volume of the digital audio data not yet outputted from the signal processing means.
An optical disc reproducing apparatus in claim 2 of the invention comprises a pickup means for detecting digital audio data recorded on an optical disc, a first storing means for storing the digital audio data detected by the pickup means, a second storing means for storing the digital audio data read from the first storing means, an input means for inputting the reproducing direction and reproducing speed of the digital audio data, a control means for controlling the reading and writing of data from/into the storing means so as to control the reading direction and reading speed of the digital audio data stored on the first storing means and second storing means based on the reproducing direction and reproducing speed inputted from the input means, and a signal processing means for converting the digital audio data read from the first storing means or second storing means into an analog audio signal and outputting the analog signal, wherein the control means controls so that the digital audio data read from the first storing means is outputted from the signal processing means and, at the same time, is written into the second storing means.
An optical disc reproducing apparatus in claim 3 or claim 4 wherein the control means stores, when the reproducing direction and reproducing speed are inputted from the input means, whether the operation is in a normal-speed reproduction mode or a pause mode, and controls so that the operation returns to the normal-speed mode or the pause mode, when the reproduction mode, which is based on the reproduction direction and reproduction speed inputted from the input means, is ended.
According to the present invention, there is provided an optical disc reproducing apparatus which is capable of forward scratch reproduction and reverse scratch reproduction.
According to the present invention, there is provided an optical disc reproducing apparatus which can start scratch reproduction operation during the reproduction of an optical disk at a normal speed and return to the normal-speed reproduction operation after the scratch reproduction is ended.